Small purple plum (6)
I believe the answer is:
damson
'small purple plum' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for damson that I've seen before include "Wild plum" , "Ma, Don's a fruit" , "Small stone-fruit for nomads" , "Dark purple plum" , "Kind of plum for nomads" .)